The car with which Red Bull Racing will hope to defend its two F1 championship crowns is running behind time, according to team principal Christian Horner.

The Milton Keynes-based team puts the delay down to its focus on retaining both the constructor and individual titles in a fraught end to the 2012 campaign, but is confident that the work being put in behind the scenes now will pay dividends when its renews hostilities with Ferrari, McLaren et al next season.

"For sure, knowing Adrian, it's going to be late," Horner quipped while appearing with Sebastian Vettel and designer Adrian Newey on Red Bull's ServusTV, "It's late in design, but the people in Milton Keynes are working tremendously hard."

Horner confirmed that, with few rule changes to be concerned by, the 2013 car would be largely based on this year's successful RB8, but that the design team would be looking to extract the maximum performance from it ahead of winter testing.

"It's an evolution because the regulation are reasonably stable," he emphasised, "But the dangerous thing in F1 is to underestimate your rivals and Ferrari, McLaren, Mercedes-Benz and Lotus, as we saw this year, are massively strong teams, and very motivated.

"We've managed to achieve some wonderful things over the last three years, and we'll be determined to retain the trophies we've worked hard to achieve, but we can take nothing for granted and that'll play a large part in our motivation going into 2013."

Newey confirmed that the pressure to keep Vettel in the title hunt right to the final round of 2012 had taken his eye off the progress being made on next year's project.

"This year was the toughest fight I've been involved in," he admitted, "and not only due to the length [of the season] and the number of races we had to do.

"In 2010, we had a very fast car, but reliability problems meant that the drivers' title went down to the last race. Last year, we could take nothing for granted, but could take things a little easier because we had pace and reliability. This year was different. The car showed flashes of pace - Sebastian won in Bahrain and Mark Webber in Monaco - but we didn't have the level of consistency that we wanted.

"As an engineer, that was very frustrating because we didn't fully understand the car and what was happening with it, but we made a step [forward] in Valencia, and again in Singapore, and that gave us the purple patch when Sebastian won four on the trot and set up the championship challenge."

Although the rulebook changes little for next season, there are some alterations that Newey and his design team will have to get their heads around between now and the first test in Spain in early February.

"The primary focus going into 2013 is that Pirelli is changing the front tyre," Newey continued, "We've got to understand how that is going to affect the aerodynamics of the car, which will be a job for the winter. We had a brief run [on the new tyres] in first practice in Brazil to get some idea, but the work will really start when we get the tyres in earnest in testing.

"In the meantime, we're just going to do our research for 2013. As Christian has said, there are absolutely no guarantees about where our car will be next year. We know what we're trying to achieve, but we don't know if that is going to be more or less than our main rivals.

"That is part of the fascination of this sport - it is difficult to predict, from year to year, what is going to happen. As close as it is - with seven winners in the first seven races of 2012 - it is incredibly tight and it will only take one team to find a tiny advantage and carry that through the year [to alter the balance of power]. We'll just do our job and push as hard as we can."

Newey also revealed that a small working group was already making progress on details of the 2014 car, looking particularly at the new engine architecture with Renault, and admitted that it may be that focus switches to the RB10 earlier than usual, despite that potentially creating 'a real stretch' on resources if the team is involved in another close battle for the 2013 championship.